U.S. Pat. No. 5,688,792 (U.S. Pat. No. 5,688,792) disclosed oxazine and thiazine oxazolidinone derivatives. The compounds are antimicrobial agents. Among them linezolid, chemically N-[[(5S)-3-[3-fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl]methyl]acetamide is the most important antibacterial agent. Linezolid is represented by the following structure:

Processes for preparation of linezolid were described in U.S. Pat. No. 5,837,870,WO 99/24393, WO 95/07271, J. Med. Chem. 39(3), 673-679, 1996 and Tetrahedron Lett., 40(26), 4855, 1999.
According to prior art processes, the 5-hydroxymethyl substituted oxazolidinones are converted to the corresponding 5-aminomethyl substituted oxazolidinones, key intermediates in the production of oxazolidinone antibacterial pharmaceuticals.
The prior art processes for preparing 5-aminomethyl substituted oxazolidinones are associated with many drawbacks. For instant in the preparation of linezolid, WO 95/07271 uses butyl lithium at very low temperature (−78° C.). It is known that the handling of butyl lithium is difficult and the person skilled in the art appreciate a process that produces the product in good yield avoiding the ‘difficult to handle’ reagents.
We have discovered novel intermediates useful for preparing oxazolidinone antibacterials. The novel intermediates can be prepared in high yields using easy to handle reagents. The novel intermediates can be converted to oxazolidinone antibacterials using common reagents, also in good yields.